1. Field of the Invention
The present invention relates to a testing apparatus for a variety of electronic components, such as semiconductor integrated circuit devices (hereinafter simply referred to as an xe2x80x9cICxe2x80x9d or xe2x80x9cICsxe2x80x9d) and a method of testing electronic components, and especially relates to a method of testing electronic components which can increase the number of electronic components to be simultaneously tested even if the number of terminals on a test head side is small and a testing apparatus for electronic components.
2. Description of the Related Art
A testing apparatus for electronic components, called a xe2x80x9chandlerxe2x80x9d, conveys a large number of ICs held on a tray to the inside of a testing apparatus where the ICs are pressed against socket terminals connected to a test head, then the IC testing unit (tester) is made to perform the test. When the test is ended, the ICs are conveyed out from the test procedure and reloaded on trays in accordance with the results of the tests so as to classify them into categories of good ICs and defective ones.
In a handler of the related art, there are some types wherein trays for holding the ICs to be tested or the tested DUTs (hereinafter referred to the xe2x80x9ccustomer traysxe2x80x9d) and trays conveyed circulating inside the handler (hereinafter referred to as the xe2x80x9ctest traysxe2x80x9d) are different, therefore, in such types of handlers, the ICs are switched between the customer trays and the test trays before and after the test, and in the testing processing wherein tests are carried out by contacting the ICs to the socket terminals, ICs are pressed against the test head while being carried on the test trays.
In such handlers, it is considered that the faster the processing speed is and the larger the number of ICs to be tested is in a certain period of time (meaning xe2x80x9cthroughputxe2x80x9d of the testing apparatus), the more preferable, however, as shown in FIG. 14, the throughput is substantially proportional to the number of ICs simultaneously pressed against the socket of the test head, that is the simultaneously tested number when in a specification requiring a longer testing time (often the case with, for example, memory ICs). For example, as shown in the same figure, in a range where the time for testing is longer, throughput of handlers of simultaneously testing 64 ICs becomes twice as much as that of the handlers of simultaneously testing 32 ICs. Accordingly, when the simultaneously tested numbers of ICs is increased, the through-put can be higher.
In order to increase the simultaneously tested numbers of ICs, however, the number of the terminals on the test head side has to be increased along with it. Thus, a test head of the related art could not be used as it was.
FIG. 13 is a schematic view of the connection relationship of the test head terminals and the socket terminals in a test procedure. In handlers of the related art, terminals on the test head side were separately provided for each of driver pins and input/output pins of the ICs (DUTs: Device Under Test). Therefore, the number of ICs capable of being simultaneously tested on the handler side is restricted by the number of the terminals on the test head side. In other words, the number of terminals on the test head side has decided the limit of the number of ICs of handlers simultaneously tested.
An object of the present invention is to provide a method of testing electronic components which can increase the number of ICs to be simultaneously tested even if the number of terminals on the test head side is small and a testing apparatus for electronic components.
(1-1) According to a first aspect of the present invention, there is provided a method of testing electronic components to judge whether the electronic component is good or defective in accordance with a response output signal by inputting a test signal to the electronic component to be tested including: a first test step of inputting a common test signal to the respective electronic components of a group of electronic components composed of a plurality of electronic components and judging in accordance with a response signal thereof whether the group of electronic component subjected to the test is good or defective as a whole; a second test step of inputting mutually independent test signals to the respective electronic components of a group of electronic components judged to be defective in the first test step and judging in accordance with a response signal thereof each of the electronic components subjected to the test is good or defective.
In the present invention, tests are carried out on a group of electronic components composed of a plurality of electronic components by using a common test signal in a first test step to detect whether the whole group of the electronic components is good or defective. At this time, when a correct response output signal can be obtained as the whole group of electronic components, all of the electronic components composing the group are judged good regardless of the fact that the test signal is common or not. Inversely, when an abnormal response output signal is obtained as the whole group, which one of the electronic components composing the group is good or defective cannot be specified. Therefore, in the present invention, a second test step is provided.
Namely, in the second test step, the electronic components composing a group of electronic components judged to be defective in the first test step are respectively input mutually independent test signals, not a common test signal. Then, in accordance with the response signal, each of the electronic components subjected to the test is judged to be good or defective. In this way, it is possible to detect which of the electronic components is good or defective in the group judged to be defective.
As a result, it is possible to perform tests simultaneously on a plurality of electronic components by using terminals on one test head side, and to increase the number of electronic components to be simultaneously tested without increasing the number of terminals of the test head.
The testing method of electronic components is especially efficient in the case where the rate of good electronic components is high because the separate tests in units of an electronic component have to be carried out only when a group of electronic components is judged to be defective.
As kinds of test signals according to the present invention is not specifically limited, and, for example, in a memory IC, in addition to address specifying signals input from the driver terminals, input signals input from the input terminals are also included.
(1-2) In the above invention, the second test step may be placed immediately after the first test step, or instead of this, a step of rearranging electronic components judged to be defective in the first test step and a step of conveying the rearranged electronic components to the second test step may be included between the first test step and the second test step.
(1-3) In the above invention, an input form of a commonly input test signal in the first test step is not specifically limited and, for example, it is input in parallel from a common terminal of a test head to respective electronic components of the group of electronic component.
Also, instead of this, as an input form of a test signal commonly input in the first test step, it is selectively input from a common terminal of a test head to respective electronic components of the group of electronic component.
In the former input form, by dividing a terminal circuit (for example a socket board) on the socket side, it is possible to simultaneously carry out tests on a plurality of electronic components by using the terminals no one test head side. While in the latter input form, by dividing the terminal circuit (for example a performance board) on the test head side, it is possible to carry out tests on a plurality of electronic components by using terminals on one test head side. In both cases, when either one of the socket side or the test head side is changed, the other side can be used as it is.
(1-4) Note that a test signal of the first test step may include a second test signal mutually independently input to respective electronic components of the electronic component group.
Also, an response output signal output mutually independently from the respective electronic components in the group of electronic components may be included in the response output signal in the first test step.
The gist of the present invention is to increase the number of electronic components simultaneously tested without increasing the number of terminals on the test head side by making test signals, which can be made common, common as much as possible. In that sense, it does not aim to make test signals common, for example, testing signals necessary for judging good or defective of a group of electronic components, which cannot be made common.
(1-5) In the method of testing electronic components of the present invention, the number of electronic signals simultaneously tested in the first and second test steps is not specifically limited and any number may be included. Especially, it is preferable that N number of electronic components are simultaneously tested in the first test step and N/2 number of electronic components are simultaneously tested in the second test step (note that N is a natural number). For example, 64 electronic components are simultaneously tested in the first test step and 32 electronic components are simultaneously tested in the second test step. In the same way, when 128, 32, 16 electronic components are simultaneously tested in the first test step, 64, 16, 8 electronic components are simultaneously tested in the second step. These numbers depend on the number of electronic components composing one group of electronic components.
(2-1) To attain the above object, according to a second aspect of the present invention, there is provided an electronic component testing apparatus having an IC socket, one end of which is connected to an electronic component to be tested and the other end is connected to a terminal of a test head, comprising a circuit for combining in parallel terminals of at least two IC sockets on the electronic component side with respect to at least one terminal of the test head.
In the present invention, since at least one terminal of a test head is provided with a circuit for dividing in parallel the terminals on the electronic component side of at least two IC sockets, when tests are carried out by using the above method for testing electronic components of the present invention, the number of electronic components to be simultaneously tested can be increased without increasing the number of terminals of the test head.
(2-2) The dividing circuit according to the present invention is not specifically limited and may be provided on the IC socket side or on the test head side. When providing the dividing circuit on the test head side, it is preferable that a switch is provided in the dividing circuit.
In either case, wherein the dividing circuit is provided on the IC socket side or the test head side, a plurality of electronic components can be tested by using terminals of one test head side, and in both cases, when either one of the IC socket side or the test head side is changed, the other can be used as it is.
(2-3) In the present invention, it is preferable to comprise a mechanism for simultaneously connecting a plurality of electronic components to terminals of electronic component side of the IC socket of a plurality of electronic components, obtaining test results for a group of IC sockets provided with the dividing circuit, rearranging a group of electronic components judged to be defective so as to correspond one electronic component to one group of the IC sockets.
By providing a reinspection mechanism for performing reinspection to a group of electronic components judged to be defective after completing tests as a group of electronic components, final judgement of whether each of the electronic components is good or defective can be automatically made.
(3) In the method of testing electronic components and an electronic component testing apparatus of the present invention, the number of electronic components composing a group of electronic components is not specifically limited and all natural numbers of two or more are included. Also, the larger the number of electronic components to be simultaneously tested in the first and second test steps are, such as 16, 32, 64, 128, etc., the higher the throughput becomes, so the more preferable it becomes. However, the number is not limited to the above and includes all natural numbers of two or more are included.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.